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4/12/17
1
CellStructureandFunc.onBIOL 100
Ch. 2
Cells
• Fundamental units of life
• Cell theory
• All living things are composed of one or more cells.
• The cell is the most basic unit of life.
• All cells come from pre-existing cells.
• Except possibly viruses
• Minimal Cell
– Plasma membrane
• Phospholipid bilayer
– Cytoplasm
• Space inside cell excluding nucleus
– Genetic information
• DNA
– Ribosomes
Cell Structure Human height Length of some nerve and muscle cells
10 m
Frog egg
Chicken egg
Una
ided
eye
1 m
100 mm (10 cm)
10 mm (1 cm)
1 mm
Ligh
t mic
rosc
ope
Elec
tron
mic
rosc
ope
100 nm
100 µm
10 µm
1 µm
Most plant and animal cells
Viruses
Nucleus Most bacteria Mitochondrion
10 nm
Lipids
Ribosome
Proteins
Mycoplasmas (smallest bacteria)
1 nm Small molecules
0.1 nm Atoms
Range of Cell Sizes
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Two Cell Types
• Prokaryotic
• Bacteria
• Archaea
• Eukaryotic
• Everything else
Prokaryotic Cells
• Average 2 µm to 8 µm long
• No nucleus
• Nucleoid (nuclear region)
• Bacterial cell wall
• Peptidoglycan
• Limited organelles
• Ribosomes
Prokaryotic vs. Eukaryotic
Figure 4.2
Prokaryotic cells Eukaryotic cells
DNA
Size
Organization
Organelles
in “nucleoid” region within membrane-bound
nucleus
much smaller much larger
always single-celled often multicellular
only one type of organelle many types of organelles
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The Eukaryotic Cell • Much larger
• 10x length
• 1000x volume
• Nucleus present
• Variety of membranous cellular organelles
• tiny specialized “organs”
• Vary in cellular metabolism
• Dependent on internal cellular membranes
• Increase areas of specialization
nuclear envelope
nuclear pores DNA
nucleolus
nucleus smooth endoplasmic reticulum
free ribosomes cytosol
mitochondria
lysosomes
Golgi complex
plasma membrane
transport vesicle
rough endoplasmic
reticulum
cytoskeleton
The Eukaryotic Cell
• Cytosol
• aqueous jelly-like fluid
• excluding nucleus
• bathes organelles
• should not be confused with the cytoplasm
• Cytosol fills cytoplasm
The Eukaryotic Cell • Plasma membrane
• outer lining of the cell
• phospholipid bilayer
• imbedded with proteins
• contains cholesterol
• controls entry and exit of many compounds
other organelles
Components of eukaryotic cells
nucleus cytosol cytoskeleton plasma membrane
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Multicellular Eukaryotes
Smooth endoplasmic reticulum
Rough endoplasmic reticulum
CYTOSKELETON:
NUCLEUS: Nuclear envelope Chromosome Nucleolus
Ribosomes
Golgi apparatus
Plasma membrane
Mitochondrion
Peroxisome
Cell wall
Central vacuole Microtubule
Intermediate filament
Microfilament
Cell wall of adjacent cell
Chloroplast
Plasmodesmata
• Plant
• No centrioles
• Cell wall (cellulose)
• Chloroplast
• Central vacuole
Multicellular Eukaryotes
Smooth endoplasmic reticulum
Rough endoplasmic reticulum
CYTOSKELETON:
NUCLEUS: Nuclear envelope
Chromosomes
Nucleolus
Ribosomes
Golgi apparatus
Plasma membrane
Mitochondrion
Peroxisome
Centriole
Lysosome
Microtubule
Intermediate filament
Microfilament
• Animal
• Paired centrioles
• No cell wall
• Flagella in some
(movement)
• Contractile vacuole
• No chloroplasts
Smooth endoplasmic reticulum
Rough endoplasmic reticulum
CYTOSKELETON:
NUCLEUS: Nuclear envelope Chromosomes Nucleolus
Ribosomes
Golgi apparatus
Plasma membrane
Mitochondrion
Peroxisome
Centriole
Lysosome
Microtubule Intermediate filament Microfilament
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Two membranes of nuclear envelope Nucleus
Nucleolus
Chromatin
Pore
Endoplasmic reticulum
Ribosomes
• Nucleus • Control center of the cell • Contains DNA
Nucleus
Ribosomes
Cytoplasm
Endoplasmic reticulum (ER)
Free ribosomes
Bound ribosomes
Ribosomes ER
Small subunit
Large subunit
• Two subunits
• Made of ribosomal
(r)RNA and proteins
• Assemble amino acids
into polypeptides
• Using transfer
(t)RNA
• Every cell has ribosomes!
Endoplasmic Reticulum
Smooth ER
Nuclear envelope
Ribosomes
Rough ER
• Rough ER (due to ribosomes)
• Makes membrane bound proteins
• Makes secretory proteins
• Smooth ER
• Synthesis of lipids
• In the liver, helps regulate blood sugar
• Drug breakdown
• Storage of calcium
• Amount of Smooth ER or Rough ER in the cells depends on the function of the cell
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The Golgi Complex
cisternal space
cisternae
Transport vesicle from RER fuses with Golgi
Protein undergoes more processing in Golgi
Proteins are sorted and shipped…
to cytosol
for export out of cell
Side chains are edited (sugars may be trimmed, phosphate groups added). to plasma
membrane
vesicle
Golgi complex
1.
2.
3.
• Receives and modifies substances
manufactured in the ER
• Finishes, sorts and ships
products
• Contents may either leave the
cell or become part of the cell’s
organelles or membrane
Lysosomes • Digestive enzymes (hydrolytic) in a
membranous sac
• Only work in a very acidic
environment
• “Stuff” that needs to be broken
down is brought into the
membranous sac (recycling)
• Engulfing bacteria
• Fusing with food vacuoles
• Embryonic development
(programmed cell death)
worn-out organelle
lysosome digestive enzymes
5. Usable molecules recycled to make new organelles. 3.
4. Waste molecules expelled from cell.
Small molecules returned to cytosol.
1.
2. Organelle broken down.
Lysosome fuses with worn-out organelle.
Mitochondria • Mitochondria
• Energy converting
organelle
• Cellular Respiration
• Converting
chemical energy in
food to chemical
energy of ATP for
cellular work
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Mitochondria and Energy
Mitochondrion
food oxygen
water carbon dioxide ATP
outer membrane
inner membrane
• Double membrane – two compartments (outer and inner membranes)
• Intermembrane space • between the membranes where
H+ build up occurs • Cristae
• increase surface area for ATP production
• ATP Synthase is embedded here
• Mitochondrial matrix • The Citric Acid Cycle is
located here
The Cytoskeleton
(c) (b) (a) Microtubules Intermediate filaments Microfilaments
Main function: changes in cell shape
Main function: maintenance of cell shape Main functions: maintenance
of cell shape, movement of organelles, cell mobility (cilia and flagella)
10 nm 7 nm 25 nm
• Internal Scaffolding
• web of protein strands
• Microfilaments
• Intermediate filaments
• Microtubules
• Provides structure
• Facilitates the movement of materials inside the cell
• Facilitates cell movement.
Plant Cells • Like animal cells, have:
• Ribosomes
• Nucleus
• RER
• Golgi
• Plasma membrane
• mitochondria
• Do NOT possess
lysosomes
nuclear envelope nuclear pores
nucleolus
nucleus
plasma membrane
cytoskeleton
smooth endoplasmic reticulum
rough endoplasmic reticulum
free ribosomes
cytosol chloroplast
mitochondrion
cell wall
central vacuole
DNA
Golgi complex
Plant cells have a cell wall, chloroplasts, and a central vacuole, while animal cells do not.
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• 3 structures not found in animal cells:
• a cell wall
• cellulose
• a large central vacuole
• provides turgor
pressure
• chloroplasts
• carry out
photosynthesis
Plant Cells
nuclear envelope nuclear pores
nucleolus
nucleus
plasma membrane
cytoskeleton
smooth endoplasmic reticulum
rough endoplasmic reticulum
free ribosomes
cytosol chloroplast
mitochondrion
cell wall
central vacuole
DNA
Golgi complex
Plant cells have a cell wall, chloroplasts, and a central vacuole, while animal cells do not.
Central Vacuole • Stores water and nutrients
• degrades waste products
• like lysosome in animal cells
Cell Wall
• Gives the plant structural strength
• helps regulate the intake and retention of water.
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Chloroplasts • Sites of photosynthesis
• Double membrane
like mitochondria
• Internal space like
mitochondria
• Contain stacks of
thylakoids (not like
mito)
sugar (food) oxygen
outer membrane inner membrane
water carbon dioxide
minerals
Structures in Plant and Animal Cells